326 over heating and boiling the gas in the carb

[wendyg66]

I have been trying to find any information on how to deal with my 66 lemans 326 that after driving it for a short period will boil the gas out of the carb. I have put on a 6 blade flex fan, increased the coolent ratio, but nothing seem to improve it. It does not boil over and the temp seem to be fine (190-200f). So would a different type of water pump help me? I have a 3 core radiator that has been rebuilt so I know it's good, but a 4 core might be better?

Any thoughts and/or experiences?
WendyG66

[Larry]

Is the gas "boiling out" while driving-- ie: vapor lock, or is it something that happens after shutting off the car and it sits?

Rarely do you hear of vapor locking in cars much past the '40s. It was more of an "old car" problem.

Gas problems are not usually a function of the cooling of the engine itself, although it can contribute to it. There are many examples that most car nuts have of a car overheating but continuing to run fine fuel-wise. This sounds to be carb orientated.

Give us a little more info and we'll get our thinking caps on.

[wendyg66]

More info on this subject: It's not vapor lock, as I know what that is. But my problem is that AFTER driving for awhile, and shutting off the engine, the gas in the carb you can hear and smell boiling out. I have an aluminum intake (edelbrock), holly carb and a composit carb spacer between them. It just seems to me that the engine block gets too hot and transfers the heat to the intake manifold and hence is like a hot plate to the carb. I have a friend that made a wooden spacer between the carb and intake, but he still has to crank for awhile to get the car started (65 lemans) 326 also. I'm looking for an "tricks" or suggestions as to how to keep the car (once shut off) from cooking the carb. Would a different type of water pump other than stock help?

Hope this info help clearify.

[Larry]

There are a lot more radical engines running that don't have that problem, so it is kinda strange. But, it is not unheard of.

You already have a spacer, so that's a plus, but it still sounds like you are having excessive heat building up after shut down. This is called "hot soak" or "percolation".

Read this article at: http://books.google.com/books?id=ClyzQHlQbjYC&pg=PA113&lpg=PA113&dq=fuel+boiling+in+carb&source=web&ots=SdSdgh_2e5&sig=fIKWkG4TUZwKGsLWC_QaR7AYdBU&hl=en&ei=S7yYScirKNCCtwe51N2pCw&sa=X&oi=book_result&resnum=7&ct=result#PPA113,M1

It is from a book about Holley carbs.

As they suggest you may wish to reroute your fuellines to cooler areas if possible and even install a deflector plate under the carb (even my 1940 Pontiac has one of those!).

Try switching fuel too and see if that helps. Some are better than others in this regard-- the newer fuels being the worse.

Also try opening your hood after shutting down just to see if that helps... not that you want to do that every time! But it's worth a try.

After cooled down, is al the gas gone from the bowl(s)? Does the accelerator pump shoot anything?

As they mention in the article, it is a trial and error process.

Pleae keep us posted.

[engineer]

what type of exhaust system are you using? headers or stock manifolds, is the heat crossover open, or plugged closed, and what choke? If Stock manifolds, is the heat riser still in place and opens freely?

[engineer]

also what fuel pump are you using? if stock, does your car have a vapor return line back to the gas tank?